Dr. Sanjay Gupta: Where is West Nile virus?

CNN's Dr. Sanjay Gupta

(CNN) -- CNN Medical Correspondent, Dr. Sanjay Gupta talked to CNN Anchor Fredricka Whitfield about the spread of the West Nile virus. Health officials are comparing notes on new human cases reported in four more states. Now there may soon be new ammunition against the deadly virus.

GUPTA: So the numbers have gone up by almost a third over the past week, and experts have predicted ... the numbers will be about 1,000 cases maybe even by the end of the season.

The worst two weeks of the season are the last week of August and the first week of September. We are getting there just about now. Thirteen deaths now, Fredricka, as well. We have been hearing some unconfirmed reports, as well, about cases in Georgia, in South Dakota. There are confirmed cases in Wyoming and Colorado.

WHITFIELD: Well, Sanjay. Let's talk about this 53-year-old Georgia man, who has not been confirmed with having West Nile, but hospital officials in his area believe that he is dealing with those symptoms, what would it take for federal authorities to confirm it? What do they need to see or understand about his condition in order to confirm him as another case?

GUPTA: Right. Well, a couple of things about that that are important. The confirmed cases actually are coming from the CDC. That's the Centers for Disease Control here in Atlanta. They are trying to have one agency in this case, the CDC, actually confirm all of the cases around the country, and that is so everyone can be sure. Basically, to confirm a case, you have to show the presence of the virus in the bloodstream or in the cerebral spinal fluid. That is the fluid that surrounds the brain in the spinal cord.

Without actually showing that that virus is present, you can't say for sure that it's a case of West Nile virus.

And I should point out as well, Fredricka, there are a lot of other things, as we've talked about, that can cause these sorts of symptoms. The flu being one of them, St. Louis virus is another one of them. There are other things that can be confused. That is why the CDC is trying to confirm all of these cases.

WHITFIELD: Now the FDA is weighing in. What is the latest from that organization?

GUPTA: Well, you know, people are starting to talk about treatment. You know, there really isn't a good treatment for the West Nile virus. What has happened recently, the FDA has OK'd a trial with a medication called Intron A (alpha interferon). This is actually tacking place in Queens, New York, and 40 people who have West Nile are actually going to be enrolled in this trial to see if the medication, which essentially works as an immune booster will actually be effective against the West Nile virus.

I should point out as well, that people are looking at anti-virals. There are anti-virals that have been effective to some degree against hepatitis. There is going to be some research to see that those medications, those anti-virals are also effective against West Nile virus.

WHITFIELD: All right, Dr. Sanjay Gupta, thank you very much.